1. Field of the Invention
The present invention relates to an ultrasonograph such as a sphygmus (pulse wave) detection apparatus or ultrasonic imaging-and-diagnosing system for sending ultrasound to a region to be diagnosed (hereinafter often referred to as a region of interest) and obtaining information about the diagnosed region based on reflected waves and, more particularly, to an ultrasonograph capable of diagnosing a region of interest at high sensitivity.
2. Description of the Related Art
Ultrasonographs for obtaining information about a biological body or a substance using ultrasound have been well known for years. Such an ultrasonograph emits ultrasonic waves to a region of an examinee or substance to be diagnosed or examined, detects waves reflected from the diagnosed or examined region, and gains information about the diagnosed region based on the results of detection. For example, in a sphygmus detection apparatus using ultrasound, ultrasonic waves are emitted toward the radial artery of an examinee, and the pulse waveform or the pulse rate is derived from the amplitude of the reflected wave or from the variation in the frequency.
One example of such an ultrasonograph is shown in FIG. 13 and has a sensor portion 600 equipped with an ultrasound-sending unit and an ultrasound-receiving unit. The ultrasound-sending unit is applied against a region to be diagnosed and emits ultrasonic waves. The ultrasound-receiving unit receives reflected waves. The side of the sensor portion 600 that is applied against the diagnosed region and the opposite side are firmly bonded to a support unit 100 such as a belt with an adhesive or the like.
In ultrasonographic diagnosis, the sensor portion 600 is used while held against the surface of the diagnosed region of an examinee or the like by the support unit 100. The sensor portion 600 is applied against the diagnosed region directly or via a layer made of a material for acoustic matching such as silicon gel.
In this ultrasonograph, however, ultrasound is also emitted toward the support unit 100 from the ultrasound-sending unit of the sensor portion 600. The ultrasound sent toward the support unit 100 is reflected off the interface between the sensor portion 600 and the support unit 100, propagates through the support unit 100, and may be received as a noise signal by the ultrasound-receiving unit. Sometimes, external ultrasonic noise may propagate through the support unit 100 and be received by the ultrasound-receiving unit. Where the ultrasound-receiving unit receives a noise signal in this way, there arises the possibility that the detection sensitivity to information about the diagnosed region based on the received ultrasound is deteriorated.
Accordingly, it is an object of the present invention to provide an ultrasonograph capable of diagnosing a region of interest (i.e., a region to be diagnosed) at high sensitivity.
This object is achieved by an ultrasonograph in accordance with a first embodiment of the invention which comprises: a sensor portion having an ultrasound-sending unit for sending ultrasound to a region to be diagnosed and an ultrasound-receiving unit for receiving waves reflected from the diagnosed region; a support unit for holding the sensor portion from its back side relative to the diagnosed region; and an information acquisition unit for acquiring information about the diagnosed region based on the reflected waves received by the ultrasound-receiving unit. An ultrasound-attenuating portion for attenuating propagation of the ultrasound is interposed between the sensor portion and the support unit.
An ultrasonograph in accordance with a second embodiment of the present invention is based on the ultrasonograph in accordance with the first embodiment described above and characterized in that the aforementioned support unit is provided with a concave or cutout portion which is located opposite to the above-described sensor portion and concave when viewed from the sensor portion, and that the space between the sensor portion and the concave portion functions as the above-described ultrasound-attenuating portion.
An ultrasonograph in accordance with a third embodiment of the present invention is based on the ultrasonograph in accordance with the first embodiment described above and characterized in that the aforementioned ultrasound-attenuating portion is made of a material that attenuates propagation of ultrasound.
The above-described object is also achieved by an ultrasonograph in accordance with a fourth embodiment of the invention which comprises: a sensor portion having an ultrasound-sending unit for sending ultrasound to a region to be diagnosed and an ultrasound-receiving unit for receiving waves reflected from the diagnosed region; a support unit for holding the sensor portion from its back side relative to the diagnosed region, the support unit having a holding portion against which the sensor portion is held and an ultrasound-attenuating portion for attenuating propagation of ultrasound through the support unit, the ultrasound-attenuating portion being close to the holding portion; and an information acquisition unit for acquiring information about the diagnosed region based on the reflected waves received by the ultrasound-receiving unit.
An ultrasonograph in accordance with a fifth embodiment of the present invention is based on the ultrasonograph in accordance with the fourth embodiment, wherein the ultrasound-attenuating portion described above is a hollow groove formed in a surface of the support member that is on the side of the sensor portion.
An ultrasonograph in accordance with a sixth embodiment of the present invention is based on the ultrasonograph in accordance with the fourth embodiment, wherein the groove formed in the support member is filled with a material that attenuates propagation of ultrasound.
An ultrasonograph in accordance with a seventh embodiment of the present invention is based on the ultrasonograph in accordance with the third or sixth embodiment, wherein the material which attenuates propagation of ultrasound is epoxy resin containing powdered tungsten or a porous material.